Pop, Sputter and Backfire Question (Carbs Changed and Forum Searched)

[Guyver]

I have a 1982 GS1100E that pops, sputters and has mild backfires on deceleration (engine braking) and sometimes pops once between shifts. I thought perhaps the carbs were at fault and I wanted to switch them out with some Mikuni RS36 carbs anyway, so I did. The bike still has the same problem. From what I gathered from my forum search this appears to be a symptom of the intake o-rings leaking. Could it be that or could both sets of carbs be running too lean and causing the problem? I just checked Bike Bandit and I don't even see the intake o-rings listed. Were they on earlier models and not on the GS1100E?

[mark]

I don't know your bike very well, but your symptoms are classic lean. Pull you plugs and see, that's the easiest way to tell. Could be O-rings (if you have them), but more likely with all your mods it sounds like a little carb tuning is probably still in order.

Sounds like you're pretty close. I had the same situation with my 850 when I put on an aftermarket pipe that raising the needles 1/2 a notch solved. My carbs and set-up are quite different from yours though..........

[Dink]

Your model does not have o-rings. Check the boots between the carbs and the head, they are possibly cracking.
BTW a mild backfire is also a strong indicator of an exhaust leak at one of the joints.

Dink

[Guyver]

Thanks for the info...

I'm going to check the plugs today and give the boots a go over again. I didn't see anything the first time. I thought I might need a valve adjustment on one side; however, the noise I've picked up on might just be an exhaust leak. If all else fails I guess its off to the shop for carb adjustments. I'd rather have them handle that stuff.

[RobGS850L]

Hey Gene,
With the bike just sitting and at idle take a can of carb cleaner or brake cleaner and spray at the areas where the boots meet the head and where the boots meet the carbs. Right where the hose clamps are. If the idle picks up you may have cracked boots (read vacuum leaks). Mine got so bad I was having popping on light decel. And yes I switched carbs thinking the same thing too.

[chef1366]

If you don't have any intake or exhaust leaks you can lessen the popping by richening your idle adjustment screws. I see you have a 4-1. I have my carbs dialed in and I still get the pop on decal from the extra air flow from the K&Ns and free flowing pipes.

[Guyver]

The Problem Appears to be Solved

After delving into what some may deem the slightest of motorcycle difficulties I have emerged unscathed. That is except for that piece of skin that instantly transferred from my knuckle to the hot header with the slightest touch and then sizzled there like so much human bacon.

I fired up the bike and checked the intake boots with some carb cleaner to no avail. I goosed the throttle a little and saw some exhaust rise from the front of the head. Upon investigation I found that all of the header bolts were kinda loose. Apparently I failed to cinch them down again after I installed them and ran the bike to get things to temp.

I tightened them down and now, other than a slight pop at rare times under some crazy acceleration, the problem is solved. My thanks for everyone's advice as it helped me get the situation rectified and my bike back on the road in short order.

Now I must say, after a smooth frontage road get on, that with the Jardine exhaust, K&N Pods and the Mikuni RS36 Flat Slides that this bike is scary fast. I understand that newer bikes are faster still but I can't see the need to go any faster than this bike can muster. That being said I am still planning on a 530 chain conversion and a Pingel fuel valve. Then I'm gonna hit the Dyno and see what the bike is producing. Thanks again folks! ~Gene